1. Field of the Invention
This invention relates to integrated circuit packaging technology, and more particularly, to a lead-on-chip (LOC) type of semiconductor package with embedded heat sink, which allows the dissipation of heat from the packaged chip and also allows the overall package size to be made small.
2. Description of Related Art
An LOC type of semiconductor package is constructed on a leadframe of the type having no die pad and which is characterized by that the packaged semiconductor chip is mounted on the back side of the leads of the leadframe. This lead-on-chip configuration allows the packaged semiconductor chip to be better electrically coupled to the leadframe and also allows the overall package size to be made very small. DRAM (Dynamic Random Access Memory) devices, for instance, are usually packaged in this LOC configuration.
With today""s advanced technology, DRAM devices are being made more increased in speed and data storage capacity, from the earlier 1 MB to the present 256 MB (megabyte). This, increased performance, however, would undesirably cause the DRAM chips to produce more heat during operation.
One solution to the heat-dissipation problem is to externally attach a thermally-conductive means to the semiconductor package to help the dissipation of heat from the packaged chip. One drawback to this solution, however, is that it would significantly increase the overall package size and manufacture cost.
Related patents, include, for example, the U.S. Pat. No. 4,862,245 entitled xe2x80x9cPACKAGE SEMICONDUCTOR CHIPxe2x80x9d; the U.S. Pat. No. 4,916,519 entitled xe2x80x9cSEMICONDUCTOR PACKAGExe2x80x9d; and the U.S. Pat. No. 4,965,654 entitled xe2x80x9cSEMICONDUCTOR PACKAGE WITH GROUND PLANExe2x80x9d; to name just a few.
It is therefore an objective of this invention to provide a new LOC package with embedded heat sink to help the dissipation of heat from the packaged chip.
It is another objective of this invention to provide a new LOC package with embedded heat sink, which allows the overall package size to be made very small.
In accordance with the foregoing and other objectives, the invention proposes a new LOC package with embedded heat sink.
Broadly recited, the LOC package of the invention comprises: (a) a leadframe including an outer-lead portion, an inner-lead portion, and a downset bond-finger portion; the inner-lead portion having a front side and a back side; (b) a semiconductor chip having an active surface and an inactive surface and being formed with a plurality of centrally-located I/O pads on the active surface thereof; the semiconductor chip being arranged on the back side of the inner-lead portion of the leadframe with the active surface thereof being insulatively attached to the downset bond-finger portion of the leadframe; (c) a plurality of bonding wires which are bonded between the respective I/O pads of the semiconductor chip and the downset bond-finger portion of the leadframe; (d) a heat sink attached to the front side of the inner-lead portion of the leadframe by means of an electrically-insulative and thermally-conductive adhesive material; and (e) an encapsulation body which encapsulates the semiconductor chip, the inner-lead portion of the leadframe, the bonding wires, and the heat sink, while exposing the outer-lead portion of the leadframe to outside.
Owing to the embedded heat sink configuration, it allows the packaged semiconductor chip to have good heat-dissipation efficiency during operation and also allows the overall package body to be made very compact in size.